demo_app/server/src/main/java/com/example/demo/configuration/MessageConfiguration.java
package com.example.demo.configuration;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@Data
@Configuration
@ConfigurationProperties(prefix = "app")
public class MessageConfiguration {
    private String message;
}
